Doxycycline is a tetracycline antibiotic used for atypical pneumonia (Mycoplasma, Chlamydophila, Legionella), tickborne illnesses (Lyme, Rocky Mountain spotted fever), chlamydia, MRSA skin and soft tissue, malaria prophylaxis, acne, and others. Key teaching: (1) absorption is significantly reduced by polyvalent cations — separate by 2 hours from dairy, calcium, magnesium, iron, zinc, aluminum-containing antacids, sucralfate, bismuth subsalicylate; (2) take with a full glass of water and remain upright for 30 minutes to prevent pill esophagitis and esophageal ulceration; (3) photosensitivity is common — apply sunscreen, wear protective clothing, avoid prolonged sun and tanning beds; (4) tetracyclines are contraindicated in pregnancy and in children under 8 years because they bind calcium in developing bones and teeth, causing permanent yellow-brown discoloration and enamel hypoplasia, with possible bone growth retardation; (5) GI side effects — nausea, vomiting, diarrhea; report severe or bloody (C. difficile); (6) hepatotoxicity, particularly with high doses or in pregnancy; (7) intracranial hypertension (pseudotumor cerebri) — report severe headache, blurred vision, papilledema; (8) candidiasis with prolonged use; (9) interactions — warfarin (INR up), digoxin (level up), oral contraceptives (possible decreased efficacy), retinoids (additive intracranial hypertension). Milk/antacid, stopping early, and crushing are not the priority.
For study reference only. Always follow current clinical guidelines and your institution’s protocols.